This article is a breath alcohol tester control circuit description. The first thing you see is the breath alcohol tester includes a number pad (state machine), will replace the existing key ignition system. The driver of the car must type the password, instead of using a key. This driver will suggest modifications breathe breathe into our analyzer. If the driver passed the exam he / she may begin auto press the start button, the starter for vehicle control. The system eliminates the key to start the vehicle, so no key. Users of the system will be given audio feedback at each stage (ie whether they are tested through the keyboard, and then a blood alcohol test). This will be the standard by integrating voice chip into the system.
Next comes breath alcohol tester. Breath alcohol tester is an electronic device used to test the blood alcohol content (BAC) in a person's blood. Several other methods to detect the presence of alcohol, such as chemical reactions, light - interference, infrared absorption, and the heat generated from the catalytic reaction in the hot platinum wire. These methods, however, have drawbacks of difficult to handle and maintain. They are also very expensive and have a very limited life span. The device uses a semiconductor sensor to analyze exhaled breath. This method is both simple and affordable. Semiconductor device provides an additional advantage is that it is robust; it is highly immune to shock and vibration, and therefore more reliable.
After introducing breath alcohol tester, here we introduce its sensors. The sensor comprises a semiconductor material mounted on a ceramic tube, which is composed of a protective layer 100 - Network - per-inch stainless steel screened. When the alcohol test machine is open, the sensor is heated to normal operating temperature. In this process, oxygen is absorbed into the semiconductor surface. This results in a depletion region is formed betw1een surface and the body of the sensor. In turn, this increases the resistance of the sensor. When drunk blowing in the sensor, alcohol semiconductor surface absorption and reaction of oxygen, are already there. This reduces the sensor's overall resistance of the percentage alcohol.
When the alcohol tester is open, the heating coil sensors are inspired from May 7805 volts voltage regulator (IC5). Through self-test circuit cycle and the warm-up period. This circuit resets itself 0 alcohol reading and set ready for the light. When drunk blowing devices and sensor detects alcohol, its resistance decreases, this change the input voltage to the detector circuit. Detector circuit is composed of a quad op amp. Calibration of the detector circuit through a second resistor (R3 and R4), each part of the control voltage input divider (R21-R23). Each section is activated when the output to go low and the sample and hold circuit will catch the maximum input value and trigger appropriate leadership. Different colors represent different alcohol content of light-emitting diodes. If the detected alcohol content exceeds the legal limit (0.1%), and the other op amp will trigger the buzzer and LED corresponds to a "restricted" level of alcohol. This indicates that too many people drink and drive.